Here's a question from a viewer who writes, "My 13-year-old son seems tired all the time.How much sleep does a 13-year-old really need?" Well, one of the big changes in puberty besidesthe obvious physical changes are the need for more sleep. And today's teenagers arethe most sleep deprived they've ever been. So, believe it or not a teenager needs about10 hours or more sleep a night. And, that's considering the fact that they don't thinkthey need that much sleep but actually their bodies do. That's actually why you see a lotof middle schools actually open later than high schools in a lot of districts, becausemiddle schoolers and the youngest teenagers need the most sleep. Their bodies are changinghormonally and physically and often they're playing sports or doing other things. So,their sleep needs are pretty high. And just in case you were wondering, you really can'tcatch up on needed sleep as a teenager during the weekend to make up for what you didn'thave on the weekday. So, I would encourage good sleeping habits. No TVs in the rooms.No computers in bedrooms, 'cause those just discourage a child from getting enough sleep.But good luck on that. The teenage years are an adventure. So, best of luck to you andyour son. Thank you.